text: The annular velocity can be calculated using one of the following formulas.
  Or
  Where:
  *AV = annular velocity in Ft/min (feet per minute)
  *PO = pump output in bpm (barrels per minute) 1 barrel = 42 gallons
  *PO = pump output in gpm (gallons per minute) 1 gallon = 0.0238095238 barrels
  *ID = inside diameter of the wellbore or casing, squared
  *OD = outside diameter of the drill pipe or tubing, squared
  *1029.4 = A conversion factor constant used to calculate the volume between the outside of a tube within  the inside of another tube, using barrels.
  *24.5 = A conversion factor constant used to calculate the volume between the outside of a tube within  the inside of another tube, using gallons.
  *Pump Output = Refers to the measurement of the quantity of a fluid (to put that fluid in motion).